The present invention relates to an apparatus for sterilizing the air of rooms and the like by means of ultraviolet radiation, and more particularly to an improved ultraviolet sterilization apparatus.
The sterilizing and bactericide action of ultraviolet radiation known as UV-C (short waves) having a wavelength between 100 and 280 nanometers is used not only for the disinfection of public and private premises, particularly hospitals and nursing homes, but even in rooms opened to the public and also in homes for hygienic and prevention purposes.
There are known devices providing for the use of low pressure mercury vapor lamps as sources of the ultraviolet radiation, which are directed upward but laterally shielded since the direct exposition to this particular radiation is harmful to the persons.
The need to control the bacterial contamination of the air has largely increased in the last years, particularly whereas this parameter can be critical, to comply to safety norms and also for the increased interest for this factor in risk areas where it can relate to the health of the people or the product shelf life.
Beside the evolution and the diffusion of fixed systems of air control in closed environments (laminar flows, negative/positive pressure rooms, high number of air exchanges per hour, absolute filters, etc.) is increasing the demand for stand alone apparatuses that can replace the centralized systems in those cases where these latter cannot be employed for their high costs of installation and management, for the arisen necessity to rapidly sterilize an environment without requiring building works and structural changes or simply because the need is restricted to some areas and it would not be economically convenient to intervene on the whole system.
Moreover movable or easily replaceable apparatuses are better fit to temporary situations such as, for instance, rooms to be restructured or for a temporarily limited need such as in presence of an infectious patient in Dialysis or Intensive care or even for the domiciliary care of immunocompromised patients, in a medical ward, in dentist's surgery, etc.
In this context there are known stand alone apparatuses that use different means to control some parameters of the environmental air: electrostatic filters for reducing the number of suspended particles (smoke and dusts), activated charcoal filters for reducing gases and unpleasant odors, absolute filters (HEPA or ULPA) or germicides ultraviolet radiation (UV-C) to reduce the bacterial charge of the air.
To avoid the side effects of the direct UV-C radiation on human beings it is often convenient to treat the air in a radiation chamber located inside the apparatus where germicidal tubes are housed and the radiation can be kept under control, forcing the room air to pass through the apparatus in the radiation chamber by means of fans and the like.
However the germicidal tubes require frequent servicing because they are negatively effected by the dust that accumulates on their surface and also because their efficiency decays with the time. The use beyond their useful life must be avoided to guarantee an efficient sterilizing action.
Dust also strongly reduces the reflecting properties of the inner walls of the radiation chamber in which the tubes are located with a consequent reduction of the apparatus efficiency.
Proper precautions must also be taken when handling and replacing the tubes since the presence of sebum, dirt and fingerprints on the tube surfaces is another frequent cause of efficiency reduction.
From U.S. Pat. No. 5,894,130 that is hereby incorporated for reference and further details on the sterilizing effects of UV radiation, it is known an ultraviolet sterilization unit having a housing attached to an air heating and cooling system and including two openings into which lamp cartridges are inserted. The lamp cartridge carries ultraviolet lamps operating at a frequency capable of sterilizing air within the system. The cartridges are configured to automatically de-energize the lamps when a lamp cartridge is removed from the housing. When the sterilization unit is a multiple lamp system, upon removal of one of the lamp cartridge is removed all lamps are de-energized, with the de-energizing of the lamps occurring before a user will view the lamp. The disclosed system is applicable to sterilization units which are inserted within the air ducts of forced air heating and cooling systems.
It is therefore desirable a system that allows to avoid the above discussed risks and disadvantages, and is capable to eliminate the problems associated with the dust and the excessive aging of the tubes, that has means to increase the efficacy of the radiation like UV-C reflectors, ensuring a proper, standardized servicing of the apparatus. According to the invention, this is made possible by the use of packages assembled in advance, that cannot be modified and where the inner components cannot be even touched by the operator and most of all is completely safe, simple and fast to be carried out.
An object of the invention is to realize an apparatus for sterilizing the ambient air in a closed environment that allows a safe use of the UV-C radiation in inhabited areas, allowing to fully exploit the germicidal properties of the device without undesired collateral effect, and restoring the previous characteristics of the apparatus at every servicing by replacing the germicidal tubes and the reflective walls of the radiation chamber, which operation can be precisely scheduled (since according to an advantageous embodiment of the invention, it is the device itself that indicates the right time interval and time expiration) and kept totally safe and carried out directly by the user without requiring skilled technician personnel with consequent advantages in terms of practicality, economy and reduction of the problems of post-sale technical assistance.